1. Field of the Invention
The invention relates to a motor able to prevent entry of foreign matter to the inside of a housing.
2. Description of the Related Art
In a motor, it is necessary to prevent washing water, cutting oil, or other foreign matter from entering the inner space of a housing in which a rotor is held. In the past, the art has been known of providing an air passage in the housing and discharging compressed air through the air passage from the inside of the housing to the outside so as to prevent the entry of foreign matter to the inner space of the housing (for example, see Japanese Patent Publication No. 2007-105850A and Japanese Utility Model Publication No. 2-051050U).
To prevent the entry of foreign matter to the inner space of a housing, it is necessary to discharge the compressed fluid at a position closer to the rotary shaft. However, in a conventional motor, if providing an air passage, the strength of the bearing which supports the rotary shaft ends up being affected. This is liable to lead to generation of abnormal noise from the bearing and shortening of the lifetime of the bearing.